Egyptian police raid a non-governmental organisation office in Cairo. Many NGOs there rely on western donors or the UN to survive. Photograph: Mohammed Asad/AP

Arab regimes have always been wary of civil society organisations. A flourishing civil society promotes active citizenship, undermining the idea that the ruling elites know best. Even charitable work, unthreatening and apolitical as it might seem, can be a sensitive matter if it highlights the state's failure to provide basic services.

For that reason, non-governmental organisations (NGOs) in Arab countries – if they are allowed at all – usually need a government permit. In Egypt, a complex legal framework minutely regulates their activities, management and finances, making it easy to harass or close them down on some technicality if the authorities take a dislike to them.

One Egyptian NGO, the Nadim centre, which provides medical and other support for victims of torture, was raided a few years ago and threatened with prosecution on a host of charges, including possession of a questionnaire about torture and books about human rights, without a permit. After a public outcry, the list was reduced to just two alleged violations: not having a first-aid kit or a fire extinguisher (both of which were on the premises at the time).

Despite the restrictions, NGOs in Egypt – especially those dealing with human rights – were more active than in many other Arab countries in the runup to the overthrow of President Hosni Mubarak and chalked up a number of successes.

Though occasional raids cause little surprise, the simultaneous raids on several organisations on Thursday are very unusual and suggest a concerted attempt to crack down on them. Some organisations try to get round the rules by registering as businesses rather than NGOs – a practice several Arab governments have recently been trying to stop.

In the poorer Arab countries, such as Egypt, there is not enough funding from local sources for most NGOs to survive, so they often depend on western donors or the UN. This gives the authorities another means to control them, by blocking transfers of money from abroad.

Dependence on outside funding also provides a further excuse to crack down by claiming they are part of a foreign plot to destabilise the country.